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Very Small Welds Advice

01-23-2012, 09:30 PM

Hi,

I need to weld a new tab onto a small steel part where the original one broke off. The piece is about 1.5 in square and is about .025" thick. There are 4 tabs that stick up vertically off each side of the square. Tabs are about 3/16" wide by 3/8" tall, also about .025" thick. The piece was originally stamped out, and then the tabs were bent up vertically. I cut a new tab, and the plan is to weld it on.

So I'm going to TIG it. I tried some experiments on similar thickness stuff, and melted the crap out of it. Any tips on how to approach this? I'm really doing it for the challenge and the learning. How much current should I be using? My machine goes down to 5 amps. Tungsten size? How about .040", Ceriated?

I am not an expert at this but I often come across small things which I want to TIG. (If they were large I would burn some flux core in my wire welder :-)

I have found the trick to these sort of welds to be a good HEAT SINK. My approach to the weld you describe would be to get a piece of copper (aluminum will do but copper is better) which I could clamp against the tab side of square piece. I would make sure I had a nice square corner on the edge of the copper where the new tab is to be welded. This will allow the copper to align the tab to the base at a 90 degree angle as well as to remove excess heat. I would also cut the new tab a little long so that it could extend beyond the base. That would allow a simple fusion weld to make the joint. No filler needed.

As to the tungsten... .040 with a sharp point is probably fine. If you were manufacturing these parts a .020 tungsten might be worthwhile. For a single weld - use what you got! If you have an inverter power source Ceriated or Lanthanated should be fine.

As to the amperage... put together some scrap pieces of similar size with the heat sink and experiment. It will not take much current but only some testing with your setup can truly answer the question.

Comment

I need to weld a new tab onto a small steel part where the original one broke off. The piece is about 1.5 in square and is about .025" thick. There are 4 tabs that stick up vertically off each side of the square. Tabs are about 3/16" wide by 3/8" tall, also about .025" thick. The piece was originally stamped out, and then the tabs were bent up vertically. I cut a new tab, and the plan is to weld it on.

So I'm going to TIG it. I tried some experiments on similar thickness stuff, and melted the crap out of it. Any tips on how to approach this? I'm really doing it for the challenge and the learning. How much current should I be using? My machine goes down to 5 amps. Tungsten size? How about .040", Ceriated?

Thanks.

If you can't dial it down enough you have to put your filler rod between the part and tungsten. Or you can box it up and ship to me.

Comment

Comment

if your machine goes down to 5 amps... it is not a machine problem... is a matter of developing the technique and skill to do it..... I do little stuff with a Dynasty 350... no probs.....
take some time and study the links I previously posted... and google "Micro TIG" it is not magic... there is just a bit of a learning curve.....

practice on stuff that does not matter first... then when you have developed the skill and confidence to do it... give it a try...

am always amazed at those that dive in clueless and are shocked that the job gets muffed up... develop the skills first...

.

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Comment

This all sounds good. Thanks. Practiced a bit and I'm to the point where I can pop off an arc and hold it at the minimum the machine will do. Almost need a magnifying glass to really see it well.

Probably make another new tab that has a bottom leg, like an "L" so I can do a lap weld, rather than an edge weld, plus more metal in the vicinity. Pretty confident now that I can do it without ruining it

Don't have any ER70... filler rod that small. What else could I use? A strand of wire off a wire wheel seems like stiff stuff. How about that?